How to mirror or flip duplicates in edit mode?
There is an easy way to do that. Set the 3D cursor in the middle between leggs (it would be probably a characters pivot point) then, set pivot point for transforms to 3D cursor and Shift+D to duplicate, then Enter or right click, then CTRL+M and choose axis on which you want to mirror the shoe by pressing X or Y. After that you should have mirrored shoe on the other side of the cursor.Like this: